1. Field of the Invention
The present invention relates to a technology for preventing a fraudulent use of an image.
2. Description of the Related Art
Conventionally, to prevent a fraudulent use of a highly confidential image, a technique of printing the image by adding a fraudulent-use preventing pattern to the image is devised. The fraudulent-use preventing pattern is added to the whole or a part of the background of the image. Upon detecting the fraudulent-use preventing pattern, an image forming apparatus psychologically inhibits a user from fraudulently using the image, or prevents a leakage of information included in the image.
For example, when an image forming apparatus such as a digital copy machine copies a printed material added with the fraudulent-use preventing pattern, a copy guard character string of “copy prohibited” or the like appears on the paper. As a result, it is possible to know that the output printed image is a fraudulently copied image.
Image forming apparatuses that, upon detecting a fraudulent-use preventing pattern, print an image by destroying the printed surface of the image in a white or grey color, are also devised. These image forming apparatuses can prevent a leakage of information included in the fraudulently used image.
For example, a digital copy machine according to Japanese Patent Application Laid-Open No. H7-273975 detects presence of a fraudulent-use preventing pattern in image data read by a scanner. When a fraudulent-use preventing pattern is detected, the-digital copy machine masks the image data (destroys the image), and discharges blank paper.
An image forming apparatus according to Japanese Patent Application Laid-Open No. 2003-8864 detects presence of a fraudulent-use preventing pattern in image data read by a scanner. When a fraudulent-use preventing pattern is detected, the image forming apparatus adds a copy guard character string or stops printing, depending on a type of the fraudulent-use preventing pattern.
However according to the conventional techniques, a processing such as a destruction of an image or an addition of a copy guard character string, carried out upon detection of a fraudulent-use preventing pattern, is determined in advance. Therefore, a user cannot optionally set a processing to be carried out when an image is fraudulently used.
The processing such as the destruction of an image or the addition of a copy guard character string is carried out inside the image forming apparatus. Therefore, a concerned party cannot instantly know the fact that an image is fraudulently used or an image is about to be fraudulently used.
Furthermore, the image forming apparatus (for example, a printer) adds a fraudulent-use preventing pattern at the time of printing the image. Therefore, the fraudulent-use preventing pattern cannot be added to the image unless the image forming apparatus having the function of adding the fraudulent-use preventing pattern.